JPS63233658A - Method for deciding read condition of radiation picture information - Google Patents

Abstract

PURPOSE:To decide an optimum read condition or image processing condition, by deciding at least either an Smax or an Smin based on a differential histogram which becomes the histogram of a picture signal in a desired picture information area by setting an optimum threshold value. CONSTITUTION:The maximum picture signal level Smax in a desired picture information range is found from the histogram, and next, a differentiation processing is applied on a pre-reading picture signal. Assuming a remarked picture element on a cumulative phosphor sheet 1 as P, and the picture signals of picture elements in the neighborhood of the remarked picture element as (a-i) as shown in figure, the differentiation processing can be performed by using a differentiation operator as a differentiation value p in the remarked picture element P is p=¦a+2d+g-c-2f-i¦+¦a+2b+ c-g-2h-i¦. The histogram(differential histogram) of the pre-reading picture signal for the picture signal whose differentiation value exceeds a prescribed threshold value is generated. Next, the minimum picture signal Smin in the desired picture information range can be obtained based on the differential histogram. In such a way, it is possible to recognize the desired picture information range exactly and easily by using the differential histogram.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for determining reading processing conditions for radiation image information, that is, reading conditions and/or image processing conditions.

(Prior art) When a certain type of phosphor is irradiated with radiation (XI!!, α rays, β rays, γ rays, electron beams, ultraviolet rays, etc.), a part of this radiation energy is accumulated in the phosphor. It is known that when this phosphor is irradiated with excitation light such as visible light, the phosphor exhibits stimulated luminescence depending on the accumulated energy. stimulable phosphor).

Using this stimulable phosphor, radiation image information of a subject such as a human body is recorded on a stimulable phosphor sheet, and this stimulable phosphor sheet is scanned with excitation light such as a laser beam to produce stimulated luminescence. A main reading is performed in which light is generated and the obtained stimulated luminescence light is read photoelectrically to obtain an image signal for visible image reproduction.The main reading image signal obtained by this main reading is subjected to image processing, and this image is generated. The applicant has already proposed a radiation image information recording and reproducing system that outputs a radiation image of a subject as a visible image to a recording material such as a photographic light-sensitive material or to a display device such as a CRT based on a processed image signal. (Unexamined Japanese Patent Publication No. 55-12429, No. 56-11395
number, etc.).

In the above system, variations in the radiation energy level range accumulated and recorded on the sheet occur due to variations in the subject or photographed region or variations in the amount of radiation exposure for each individual image.

However, in the above system, the recorded image information accumulated and recorded on the sheet of each image, especially the range of the radiation energy level accumulated and recorded on the sheet of the above-mentioned individual image, etc. is known in advance, and the By performing the main reading according to reading conditions such as reading gain and recording scale factor appropriately determined based on the recorded image information, it is possible to eliminate the adverse effects caused by fluctuations in the radiation energy level range recorded in each image. IIIwI who does not receive such things! Visible images with excellent interpretation aptitude,
That is, for example, it is possible to obtain a visible image in which necessary subject image information is always displayed in a density range suitable for observation and interpretation.

In addition, in the above system, in order to obtain a visible image suitable for diagnostic purposes, for the main reading image signal obtained by main reading, the imaged area (head, chest, abdomen, etc.) of each image is Image processing is performed according to image processing conditions such as gradation processing conditions determined based on the imaging method (simple imaging, contrast imaging, etc.). However, for example, if the actual reading is not performed in accordance with the reading conditions appropriately determined based on the recorded image information of each individual image as described above, the above image processing conditions may be limited to the above-mentioned imaged parts, dancing method, etc. It is preferable to make a decision by taking into consideration the recorded image information of each individual image that has been grasped in advance.By doing so, for example, it is possible to determine the suitability for observation and interpretation in which the necessary image information is displayed in the appropriate density range and is suitable for the purpose of diagnosis. An excellent visible image can be obtained.

As a method for grasping recorded image information prior to such book reading and image processing, a method disclosed in Japanese Patent Application Laid-Open No. 58-67240 is known. This method uses excitation light of a lower level than the excitation light that should be irradiated during the main reading for reading the image signal for visible image reproduction, and uses excitation light that is stored and recorded in the stimulable phosphor sheet in advance prior to the main reading. It performs pre-reading to read the recorded image information that is being read, and determines reading conditions or image processing conditions based on the recorded image information grasped by this pre-reading, that is, the pre-read image signal obtained by pre-reading.

Note that if only the image processing conditions are determined based on the recorded image information, it is sufficient that the recorded image information is known before image processing, and in this case, the main reading image signal, which is the recorded image information itself, has already been obtained. Therefore, the image processing conditions can be determined based on this main reading image signal, and it is not necessarily necessary to perform pre-reading as described above.・
On the other hand, the reading conditions and image processing are performed based on the pre-reading image signal and the main reading image signal used in determining the image processing conditions (hereinafter, both signals are combined as necessary and referred to as the image signal for determining the conditions). One method for determining the conditions is to obtain the maximum image signal level 5IlaXa and minimum image signal level 31in of the desired image information range from the image signal carried by the image signal for condition determination, and calculate
A method of determining reading conditions and image processing conditions from 3 minutes has been considered.

A specific method for determining reading conditions based on such image signals for determining conditions is, for example, the method described in Japanese Patent Application Publication No. 17TL [60-156055] previously filed by the present applicant. , look-ahead image signal (image signal level)
At the same time, the maximum image signal level S max and the minimum image signal level 5Ilin of the desired image information range are determined from this histogram, and this S nax
and 3 min are the maximum density D raax and minimum density Qn of the appropriate density range in the visible output image, respectively.
A method has been considered in which reading conditions for main reading are determined to correspond to the maximum signal level Q nax and minimum signal level Qlin of the desired input signal range in the image processing means determined by in.

In addition, the image processing conditions are determined based on the image signal for determining the conditions.
For example, as a specific method for determining the gradation processing conditions, for example, the same method as above, that is, the image signal for determining the conditions (
(image signal level), and from this histogram, determine the maximum image signal level 5 lax and minimum image signal level 3 min of the desired image information range,
These Smax and 31 inches are respectively the maximum signal level R1lax and minimum signal level of the desired input signal range in the image reproduction means (visible image output means) determined by the maximum density Diax and minimum density DIin of the appropriate density range in the visible output image. A possible method is to determine the gradation processing conditions so as to correspond to Rl1in.

In the above, reading conditions refer to various conditions that affect the relationship between the input and output of the reading means, for example, the relationship between the input (stimulated luminescence light amount) and the output (electrical image signal level) of the photoelectric reading means. It is a general term for conditions such as, for example, reading gain (sensitivity) and scale factor (latitude) that determine the relationship between input and output, or the power of excitation light in reading.

Furthermore, in the above, the image processing condition is a general term for various conditions that affect the relationship between input and output in the image processing means, and means, for example, gradation processing conditions, spatial frequency processing conditions, and the like.

Furthermore, in the above, the fact that the excitation light used for pre-reading is at a lower level than the excitation light used for main reading means that the effective energy of the excitation light that the stimulable phosphor sheet receives per unit area during pre-reading is lower than the excitation light used for main reading. means smaller than that of .

(Problems to be Solved by the Invention) However, in the image information carried in the pre-read image signal and the actual read image signal, which are the image signals for determining the conditions, for example, there is not only desired image information but also various unnecessary components. 3nax and 3m1n of the desired image information range cannot be appropriately determined due to the presence of unnecessary image information. If, as in that case, the obtained 3Ilax and 3iin are not appropriate values, the reading conditions and image processing conditions determined based on them will also be inappropriate, and in the end, even if the obtained values are not appropriate, the reading conditions and image processing conditions determined based on them will be inappropriate. It becomes difficult to reproduce visual images.

An example of such a case is a case where imaging is performed with the irradiation field apertured. In other words, in order to avoid irradiating radiation to areas that are not necessary for humane diagnosis,
Alternatively, if radiation is applied to areas unnecessary for diagnosis, scattered radiation will enter areas necessary for diagnosis from that area, reducing contrast resolution. To prevent this, when recording radiation image information (R shadow), The irradiation field may be narrowed down.

However, when the radiation irradiation field is narrowed down in this way, the scattered radiation generated from the subject in the irradiation field usually enters the irradiation field on the stimulable phosphor sheet, and the highly sensitive stimulable phosphor sheet Since this scattered radiation is also accumulated and recorded,
The histogram of the image signal (image signal level) obtained by pre-reading and actual reading includes both edge signal levels based on these scattered rays. The image signal level outside the irradiation field on the sheet based on this scattered radiation may be higher than the image signal level within the irradiation field.
From the obtained histogram, it is difficult to distinguish between the image signal levels inside and outside the irradiation field. Therefore, when determining 3iax and 3m1n from the histogram as described above and determining reading conditions and image processing conditions from this, it is assumed that the minimum value of the image signal level within the irradiation field is 3nin.
However, there may be a case where the minimum value of the image signal level due to the scattered radiation outside the irradiation field is set to Sm1n. In this way, the minimum value of the image signal level outside the irradiation field is 31
If it is set as in, the value is generally lower than the minimum value of the image signal level within the irradiation field, so scattered radiation that is unnecessary for diagnosis during main reading and image processing will be recorded in the low W1 degree machine, and therefore it will be necessary for diagnosis. The density of the image becomes too high in such areas, resulting in a decrease in contrast, making it difficult to make a satisfactory diagnosis.

In other words, when shooting with a narrowed irradiation field, scattered rays generated from the subject enter the irradiation field on the sheet,
The image signals grayed out by pre-reading and main reading will include those based on these scattered rays (carrying unnecessary image information), so reading conditions etc. are determined based on such image signals. However, it is difficult to determine optimal reading conditions, etc., and as a result, it is difficult to obtain visible images that are suitable for observation and interpretation.

Therefore, when trying to determine reading conditions and image processing conditions based on pre-reading or main-reading image signals using the method described above, it is necessary to avoid the adverse effects of unnecessary image information such as image information of outside irradiation areas, and to always make appropriate decisions. Find the desired image information range smax, 311 inches, and calculate its 5nax,
It is desirable to determine those conditions based on Sm1n.

Note that the above problem can occur regardless of the type of recording medium on which radiation image information is recorded, that is, regardless of whether the recording medium is a stimulable phosphor sheet or not.

In view of the above-mentioned circumstances, it is an object of the present invention to provide an appropriate 5n of desired image information range without being affected by signals based on unnecessary image information even if the image signals for determining conditions include signals based on unnecessary image information.
Find ax, 3nin, and find its Smax, 311
An object of the present invention is to provide a method for determining reading processing conditions for radiographic image 9 information, which can determine appropriate reading conditions and image processing conditions based on in.

(Means for Solving the Problems) In order to achieve the above object, the method for determining reading processing conditions for radiation image information according to the present invention determines the maximum range of desired image information from the image signal for determining conditions that carry radiation image information. In the method of determining the image signal level 3 rmax and the minimum image signal level 3iin and determining the reading processing conditions for radiation image information based on the 5laX and 5Ilin, at least one of the above 311aX and 3 nin,
It is assumed that ¥ft5ll is determined based on the difference histogram of the image signal for determining the condition.

The reading processing conditions mentioned above mean reading conditions and/or image processing conditions.

The above-mentioned image signal for determining conditions refers to an image signal that carries symmetric radiation image information and can be used to determine reading processing conditions. For example, when the recording medium is a stimulable phosphor sheet, The above-mentioned pre-read or main-read image signals, etc. correspond to this.

The differential histogram of the image signal typically refers to a histogram of the image signal of pixels for which the absolute value of the differential value of the image signal is equal to or greater than a predetermined threshold, but not only such a histogram, but also It also includes histograms based on such histograms with various incidental changes made thereto.

The above-mentioned determination based on the difference histogram means determination using the difference histogram, and a specific method is, for example, to set the maximum and minimum image signal levels of the difference histogram to 3nax and 31, respectively.
One example is a method for determining in, but the method is not necessarily limited to this method, and various other methods can be used. Of course, it is also possible to take into consideration not only the difference histogram but also other information.

If only one of the above 5reax and 811in is determined based on the difference histogram, the remaining 5Ilax or Sm1n may be determined by any method, but is limited to the method of determining it based on the ordinary image signal histogram as described above. It is not something that will be done.

The specific method of determining the reading processing conditions based on the above-mentioned 3nax and 31in is also the same as the above-mentioned 5reax and 3m1.
n is Qnax, Qmin, Rmax, Rmin
It is not limited to those determined to correspond to
Various other techniques can be used.

The method of differentiation when creating the above-mentioned difference histogram may be either first-order differentiation or higher-order differentiation. Furthermore, in the case of discretely sampled images, differentiating is equivalent to finding the difference between adjacent image signals. Existing nearby means not only existing adjacent to each other, but also includes, for example, existing every other location.

(Function) If an image has an area where desired image information is recorded and an area where unnecessary image information is recorded, generally,
The image signals in the desired image information recording area have large level fluctuations among the image signals of neighboring pixels, and the image signals in the unnecessary image information recording area have small level fluctuations among the image signals of neighboring pixels. For example, when the chest of a human body is photographed with the irradiation field apertured, the chest area may be smaller than the desired recorded information area (the area where the radiation did not pass through the chest and directly entered the recording medium) or the area outside the irradiation area. Unnecessary image information areas such as areas have little fluctuation in image density, that is, little fluctuation in level between image signals.

Therefore, when the image signal is differentiated, the differential value of the desired image information area becomes larger than that of the unnecessary image information area, so an appropriate threshold value is determined experimentally and empirically, taking into consideration the positive area, the imaging method, etc. If this is done, it becomes possible to distinguish whether the image signal is from a desired image information area or an image signal from an unnecessary image information area, depending on whether the absolute value of the differential value is larger or smaller than the threshold value.

Therefore, if a differential histogram is created using an appropriately set threshold value, the differential histogram will be a histogram consisting only of image signals within the desired image information area, or a histogram close to it.

(Effects of the Invention) The method for determining reading processing conditions for radiation image information according to the present invention is based on a difference histogram that can be a histogram of only image signals within a desired image information area by appropriately setting a threshold value as described above. te5lax, 5ni
Since it determines at least one of n, it is possible to obtain a more appropriate desired image information range of 3iax or Smin than, for example, when determining it based on a conventional ordinary image signal histogram. Appropriate reading conditions and image processing conditions can be determined, contributing to the output of visible images with excellent observation and interpretation aptitude.

(Embodiments) Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.

In the embodiment described below, the present invention is applied to a radiation image information recording and reproducing system using the above-mentioned stimulable phosphor sheet.

First, an embodiment will be explained in which reading conditions for main reading are determined based on a pre-read image signal which is an image signal for determining conditions.

First, a pre-read image signal is read from a stimulable phosphor sheet on which radiographic image information of a part of a human body, which is a subject, is recorded, by the above-described pre-reading. Note that it is assumed that the radiation image information of this subject is recorded with the irradiation field apertured.

Next, a histogram of this read-ahead image signal is created. An example of this histogram is shown in FIG. 1(a). In general, the histogram of an image signal exhibits a somewhat characteristic pattern depending on the area to be imaged, the imaging method, etc. Therefore, if you examine the histogram in consideration of the area to be imaged and the imaging method, which parts will contain the desired image information. It is possible to roughly know which part of the area is the unnecessary image information area. For example, in the histogram shown in FIG. 1(a), part A is the image signal of the outside irradiation area, part 3 is the image signal of the blank area, and the remaining part C is the desired image information area. can be judged.

However, with this method of making judgments based on histograms, depending on the area to be imaged, the imaging method, whether or not the irradiation field is apertured, etc., it may be possible to make a somewhat clear judgment, or it may only be possible to make an extremely vague judgment. be.

In the case of this example, the maximum image signal level in the desired image information range can be determined with some degree of clarity, but the minimum image signal level is determined because there are many image signals caused by scattered radiation incident on the outdoor irradiation area in the low level area. , and since they overlap with the low-level side of the desired image information range, it is difficult to make a clear judgment.

Therefore, first, only the maximum image signal level 3 rmax in the desired image information range is determined from this histogram.

Next, the pre-read image signal is subjected to differential processing. Note that, before performing this differential processing, appropriate smoothing processing such as smoothing may be performed. Differential processing can be performed in various g ways as mentioned above. For example, in FIG. 2, the pixel of interest on the stimulable phosphor sheet 1 is P, and the image signals of the surrounding pixels are a as shown in the figure. -i, the differential value Δp at the pixel of interest P is Δp= l a+2d+g−c−2f −i 1+ I
This can be done using a differential operator such as a+2b+c-q-2h-i 1.

After completing the above differential processing, it is examined whether each differential value is greater than or equal to a predetermined threshold value, and the histogram ( (difference histogram). Note that the above-mentioned predetermined threshold value is for distinguishing between the differential value in the desired image information area and that in the unnecessary image information area, and its size is determined experimentally and in consideration of the imaging site, contrast method, etc. It can be determined empirically. An example of a difference histogram created in this way is shown in FIG. 1(b).

Next, the minimum image signal level 3iin of the desired image information range is determined based on the difference histogram.

The difference histogram becomes a histogram of only the image signals within the desired image information area by appropriately determining the threshold value as described above. Therefore, by using this difference histogram, it is possible to accurately and easily know the desired image information vl range. As a result, the above 3m1n can also be determined more accurately and easily. Various methods can be considered as specific methods for determining this 311 inches. In this example, Fig. 1 (
As shown in b), the minimum side g1 in the difference histogram
Although the signal level was set to 31 inches as it is, other methods may be used, for example, by setting a predetermined threshold fM Th 1 as shown in FIG. A method in which the level is set to 3m1n, or a cumulative histogram for the difference histogram is created as shown in Figure 1 (C), and points where the cumulative frequency exceeds a certain threshold value Thz or the entire cumulative frequency in this cumulative histogram are It is also possible to adopt a method in which the image signal level at a point where the ratio to the threshold T h exceeds a certain threshold value T h 3 is set to 5Ilin.

As described above, the desired image information range Smax, Sm
After determining 1n, read conditions for main reading are determined based on 3nax and 31in. This 3max.

Although various methods can be used to determine the reading conditions based on 31 inches, an example thereof will be described below with reference to FIG.

That is, in the H9Aa image information recording and reproducing system,
Normally, as mentioned above, an electrical image signal is obtained from the stimulated luminescence light by a photoelectric reading means according to reading conditions, and this signal is subjected to various signal processing by an image processing means, etc. at a rate determined according to the imaging site and imaging conditions. Tone processing is performed in accordance with tone processing conditions, and this signal is reproduced and recorded as a visible output image on a photographic light-sensitive material or the like by an image reproducing means. In this output image, there is a density range suitable for observation and interpretation, and generally this appropriate density range ([) lax −11 inch) is predetermined, and the reproduction conditions of the image reproduction means (input to the reproduction means and Since the conditions determining the relationship with the output from the means are also predetermined depending on what kind of image reproduction means is used, the optimal II range<DIlax −
The input signal level <RIax to Rmin) to the image reproducing means corresponding to 0nin) is uniquely determined by this image reproducing condition. Furthermore, since the gradation processing conditions in the image processing means are also predetermined depending on the part to be photographed, the photographing method, etc., the input signal to the image processing means corresponding to the input signal level (Rla× to R11in) to the image reproduction means is The level (QlaX −Qllin > is uniquely determined by this gradation processing condition. Therefore,
An input signal level range (Q l
ax~Qmin) is uniquely determined according to predetermined @sub-processing conditions and image reproduction conditions. Therefore, the reading conditions are set so that S iax and 3m1n obtained as above correspond to Q nax and Q lin determined as above.

In addition, 3max 13m1n $Qllax, Qn
Setting the reading conditions to correspond to in means that the range of the image signal level (3n+ax to 31Iin) in pre-reading is the image signal level (Q n+ax
This means setting the reading conditions so that the data is read as ~Qiin). For example, the reading conditions used for pre-reading are shown in Figure 3 after taking into account the difference in excitation light energy between pre-reading and main reading. Shift and rotate around the point to create Sl'1lax, 51in.
The reading conditions for main reading may be set so that Qllax and Qnin correspond to Qllax and Qnin. Note that shifting the reading conditions as shown in the figure means changing the reading gain.
Rotating means changing the recording scale factor. Furthermore, the reading conditions are not limited to the linear one as shown in the figure, but may be curved.

Next, 3n+ax, 5ni determined as above
An embodiment in which tone processing conditions, which are one of the image processing conditions, are determined based on n will be described with reference to FIG. 3 as well. Examples described below include 5IlaX, 3n
This is to determine the conditions for performing gradation processing on the actual reading image signal when the actual reading is performed in accordance with reading conditions that are appropriately determined based on the imaging site, imaging method, etc., and not based on the in.

In this case, since the reading conditions for the main reading are determined appropriately, the image signal level (3nax - 3nin) in the pre-reading determined as above is read as (Siax' ~ Sm1n') in the main reading. , this does not necessarily apply to the above (Q raax ~ Qlli
n ) does not match, so if this continues, it will not be possible to display the desired image information range within the appropriate range (1) nax - Diin ).

Therefore, the desired image information range of 3+1 a and the actual reading image signals 5IlaX' and 3nin' corresponding to the pre-reading image signals 5nax and 3nin, taking into account the reading conditions of the actual reading and the like,
The gradation processing conditions are determined so that this <5nax' to 5nin') is output as the image processed (Riax - RIIin).

Gradation processing is a process in which each image signal input to an image processing means (gradation processing means) is converted to a level by π under certain conditions, and then outputted.The certain condition is the gradation processing condition. , and is usually represented by a nonlinear gradation curve.

The purpose of such gradation processing is to obtain a preferable visible output image suitable for diagnostic purposes, depending on the imaging conditions such as the contrast area such as the head or chest and the imaging method such as simple or contrast imaging. Therefore, in general, a basic form of nonlinear gradation processing conditions that has the most preferable pattern for each shooting condition is determined in advance, and when gradation processing of each image is performed, it is determined in accordance with the shooting conditions of both cases. It is preferable to select an appropriate basic form of gradation processing conditions and perform gradation processing using this basic form.

In this embodiment as well, in this way, an appropriate one is selected from among the basic shapes of gradation processing conditions predetermined according to the image shooting conditions, and it is modified. As shown in Figure 3, it is positioned and used so that 3iax' and 5nin' are output as Rlax and R11n by shifting in the vertical direction or rotating around a predetermined center point K. The gradation processing conditions to be used are determined.

Note that the gradation processing conditions are not limited to the nonlinear ones determined by the shooting conditions as described above, but may also be linear ones. In that case, one predetermined straight line may be used as the above case. Similarly, rotate or shift 5raax', 31in' to Rlax, Rm
The gradation processing conditions to be used are determined by positioning so that it is output as in. The determination of gradation processing conditions by this method is not based on the imaging site or imaging method, but is performed based only on the desired image information range of 5nax and 3nin.

One embodiment of the radiographic image information recording and reproducing system is one in which main reading is performed immediately without performing the above-mentioned pre-reading. In this case, the main reading is performed according to the reading conditions appropriately set based on the imaged part, the imaging method, etc., and the gradation processing conditions are determined based on this main reading image signal. It is possible, and a specific method is, for example, similar to the specific method of determining l@ tone processing conditions based on the pre-read image signal described above, to create a histogram of the main reading image signal and obtain 5Ilax, and to calculate the main reading image signal. Create a difference histogram of the image signal and 31N
Find in, this 511aX, 3nin is Rnax
, Rmin may be determined.

In each of the above embodiments, a histogram of only the pixel gA signal at a pixel where the absolute value of the differential value of the pre-read or main-read image signal is equal to or higher than a predetermined threshold is used as the differential histogram, but incidental changes may be made. For example, it is also possible to use a histogram of only the image signals at pixels whose voltage is equal to or higher than a predetermined threshold value, and further weight the frequency by the absolute value of the differential value.

Furthermore, in each of the above embodiments, 3 max is first obtained from the normal histogram, and Sm1n is obtained from the difference histogram, but 5 nin is obtained from the normal histogram.
3nax may be calculated from the difference histogram, or furthermore, both 5IlaX and 5llifl may be calculated from the difference histogram. When calculating Smax from the difference histogram, the same method as when calculating 31 inches from the difference histogram described above can be adopted.

As described above, the method for determining reading processing conditions for radiation image information according to the present invention is based on a difference histogram that can eliminate unnecessary image information with high accuracy.
Since nin is determined, more appropriate S nax and/or S lin can be obtained, and from the results, appropriate reading processing conditions can be determined.

Note that the present invention can be modified in various ways without departing from the gist thereof, and is not limited to the above-described embodiments.

[Brief explanation of drawings]

Figure 1 (a) is a histogram of the image signal, Figure 1 (b)
1(C) is a diagram showing a cumulative histogram for the difference histogram of FIG. 1(b), and FIG. 2 is a diagram for explaining an example of a method for differentiating image law signals. , FIG. 3 is a diagram showing the relationship between the density of the visible output image and the image signal. Figure 1 Rui Ning 2 Shihe Lu

Claims (1)

[Claims] The maximum image signal level Smax and the minimum image signal level Smin of the desired image information range are determined from the image signal for determining conditions that carry radiation image information, and the maximum image signal level Smax and the minimum image signal level Smin are
In the method for determining reading processing conditions for radiation image information based on in, at least one of the Smax and Smin is determined based on a difference histogram of the image signal for determining the conditions. How to determine reading processing conditions.